We are developing iron-57 Nuclear Magnetic Resonance (NMR) as an experimental method for use in the Biomedical Sciences. Numerous molecules essential to life are constructd about iron-containing central cores. Among these are hemoglobin, ferridoxin and the cytochromes. To date, no physical chemical methods have allowed direct study of the central metal environment of these proteins. Iron-57 NMR, i.e., the direct detection of the iron NMR signal, is being developed for that purpose. Formerly, we reported results of an iron-57 NMR investigation of characteristic relaxation times and chemical shifts of some iron compounds. The data furnished information on the chemical shifts range of iron coordinated to nitrogen, substituent effects on iron-57 chemical shifts, and relaxation mechanisms for iron-57, and thus provide the basic parameters needed for further development of iron-57 NMR. Most recently, the first observation of Fe57 NMR in a protein, carbonmonoxymyoglobin, was achieved together with a determination of Fe57 relaxation times and chemical shift anisotropy.